JPH0566372U - Mechanical seal device - Google Patents

Abstract

(57) [Abstract] [Purpose] Rotating ring 3 and spring 2 fixed to rotating shaft 2.
In a mechanical seal device that forms a shaft sealing surface with a fixed ring 5 that is pressed toward the rotating ring 3 by 0 to seal between a high pressure chamber and a low pressure chamber, an operating gap of the shaft sealing surface is ensured even at low speed rotation. To prevent damage caused by contact between the rotating ring 3 and the fixed ring 5. [Structure] A high pressure chamber 27 containing a slide plate 26 is provided behind a spring that presses the back surface of the fixed ring 5, and a gas supply device 29 is connected to the high pressure chamber 27 to reduce the gas pressure during low speed rotation. This reduces the amount of compression of the spring 20 to obtain the required operating clearance.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a mechanical seal device applied to a shaft seal portion of a high-pressure rotary machine such as a gas compressor or a pump.

[0002]

[Prior Art]

 An outline of a conventional mechanical seal device will be described with reference to FIGS. 2 and 3. FIG. 2 is an axial sectional view showing a main part of the mechanical seal device, and FIG. 3 is an end view of the rotary ring as seen from the shaft sealing surface side.

In these drawings, reference numeral 1 is a casing, 2 is a rotating shaft, 3 is a rotating ring fixed to the rotating shaft, 4 is a spiral groove, and 5 is attached to a casing 1 surrounding the rotating shaft 2. , A fixed ring that forms a shaft sealing surface together with the rotating ring 3, 6 is an annular groove that divides the fixed ring 5 into a bearing portion and a seal portion, 7 is a communication hole that connects the high pressure chamber P ₁ and the annular groove 6, and 8 is a shaft Sleeve, 9 is an O-ring, 10 is a pin for preventing rotation, 11 and 12 are O-rings, 13 is a key, 14 is a shaft sleeve, 15 is a bolt for fixing the shaft sleeve 8 and the shaft sleeve 14, 16 is a fixing ring 5 is a support ring, 17 is a pin, 18 and 19 are O-rings, 20 is fixed to the rotating ring 3 through the support ring 16, a spring for pressing the ring 5, 21 is a seal housing, 22 is an O-ring, and 23 is Pi , 24 retaining ring fixed ring 5 so as not to protrude from the seal housing 21, 25 is a nut for fixing the shaft sleeve 14 in the axial direction, P ₁ is the high pressure chamber, P ₂ represents the low-pressure chamber.

When the rotary shaft 2 rotates, the rotary ring 3 fixed thereto also rotates, and when the rotational speed exceeds a predetermined number, the fixed ring 5 floats above the rotary ring 3, and the gap between the high pressure chamber P ₁ and the low pressure chamber P It is automatically adjusted depending on the differential pressure from ₂ and the number of revolutions.

FIG. 4 shows a balance state of forces acting on the fixing ring 5. In this figure, W _B is the bearing fluid reaction force, W _SL is the seal gap inner reaction force, W _T is the force due to the seal differential pressure, and W _S is the spring pressing force. Here, the bearing fluid reaction force W _B must be W _B = W _T + W _S −W _{SL when the} seal differential pressure and the pressing force of the spring are applied. Also, the bearing fluid reaction force W _B is a function of the bearing clearance and the shaft rotation speed. Therefore, in order to balance the forces acting on the seal ring in accordance with the seal differential pressure and the rotation speed condition, The clearance, that is, the seal clearance, is automatically adjusted.

FIG. 5 shows the floating characteristics of the fixing ring. According to this figure, the fixed ring starts to levitate at a certain number of revolutions, and after a certain number of revolutions, the change in the amount of uplift tends to decrease.

[0007]

[Problems to be solved by the device]

 By the way, in the steam turbine, a method of operating for a long time at a low speed rotation called turning is used to prevent thermal deformation of the shaft. Therefore, in the conventional mechanical seal device, the fixed ring does not float at a low rotational speed because the fixed ring has a characteristic that it does not float at a certain rotational speed. Therefore, when the mechanical seal device is used in the turning operation, the rotating ring and the fixed ring come into contact with each other and the fixed ring is damaged.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a mechanical seal device capable of levitating a fixed ring even at a low rotational speed.

[0009]

[Means for Solving the Problems]

 For the above object, according to the present invention, a high pressure chamber is formed by forming a shaft sealing surface with a rotating ring having a plurality of spiral grooves on the shaft sealing surface and a fixing ring separated into a seal portion and a bearing portion by an annular groove. In a mechanical seal device that seals between a low pressure chamber and a high pressure chamber, a high pressure chamber that is provided behind a spring that presses the fixed ring against the rotary ring and that has a slide plate that can change the compression amount of the spring, A mechanical seal device is provided, which is provided with a gas supply device that communicates with the high-pressure chamber and supplies gas thereto.

[0010]

[Action]

 According to the above means, the pressure of the gas supplied to the high pressure chamber is changed to change the compression amount of the spring via the slide plate, thereby changing the pressing force of the spring of the fixed ring.

[0011]

【Example】

 Hereinafter, a preferred embodiment of the present invention illustrated in FIG. 1 will be described in detail. In FIG. 1, the same elements as those shown in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the figure, reference numeral 26 is a slide plate for changing the compression amount of the spring 20, 27 is a high pressure chamber, 28 is an air supply hole, 29 is a gas supply device for supplying a gas pressure to the high pressure chamber 27, and 30 and 31 are O. Shows the ring.

During low speed operation, the gas pressure supplied from the gas supply device 29 to the high pressure chamber 27 is reduced. Then, in response to this, the slide plate 26 installed in the high-pressure chamber 27 moves to the right side in the drawing, and the spring 20 expands by that amount and its compression amount decreases, so that the spring shown in FIG. The pressing force W _S decreases. As a result, the value on the right side of the above-mentioned balance formula W _B = W _T + W _S −W _SL of the mechanical seal device becomes small, so that the bearing fluid reaction force W _B is balanced in this mechanical seal device. It becomes smaller and self-aligns. Since the bearing fluid reaction force W _B is proportional to the working clearance, the bearing clearance is aligned so that the working clearance is increased.

Therefore, even during low-speed rotation, it is possible to operate with a large operating clearance between the rotary ring 3 and the fixed ring 5, and it is possible to prevent contact between the rotary ring 3 and the fixed ring 5.

[0015]

[Effect of the device]

 As described above, according to the present invention, the spring mounting portion is provided with the high-pressure chamber in which the slide plate is installed, and by sliding the slide plate, the spring force for pressing the fixing ring is reduced. The mechanical clearance of the mechanical seal device can be increased, the contact between the rotating ring and the fixed ring can be prevented, and the mechanical seal device can be operated stably.

[Brief description of drawings]

FIG. 1 is an axial sectional view of an essential part showing an embodiment of a mechanical seal device according to the present invention.

FIG. 2 is an axial cross-sectional view of an essential part showing an example of a conventional Mekaranil seal device.

FIG. 3 is an end view showing an example of a rotating ring.

FIG. 4 is an explanatory diagram showing a balance state of forces acting on a fixing ring.

FIG. 5 is a diagram showing a floating characteristic of a fixing ring.

[Explanation of symbols]

 2 rotary shaft 3 rotary ring 5 fixed ring 6 annular groove 16 support ring 20 spring 26 slide plate 27 high pressure chamber 28 air supply hole 29 gas supply device

Claims (1)

[Scope of utility model registration request] 1. A shaft-sealing surface is formed by a rotary ring having a shaft-sealing surface provided with a plurality of spiral grooves and a fixed ring separated into a seal portion and a bearing portion by an annular groove to seal between a high-pressure chamber and a low-pressure chamber. In the mechanical seal device, a high pressure chamber, which is provided behind a spring that presses the fixed ring against the rotary ring and has a slide plate capable of varying the compression amount of the spring, is connected to the high pressure chamber. A mechanical seal device comprising a gas supply device for supplying gas.